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Preparing Your Mare for Breeding Season

Preparing Your Mare for Breeding Season

  1. I have a mare that has had one foal. She is having a difficult time getting bred and I have been told her issue is retained fluids. Suggestions? (View Answer)

    Some mares have difficulty conducting a normal pregnancy to term, but retaining fluids post breeding is just one in a long list of problems. There are several factors involved here. Mares over the age of about 13 years have reached their reproductive peak and we can expect some challenges with this group.  The fact that your mare has had a foal increases our odds for a fertile breeding, but age will become a factor. Careful management of difficult mares can markedly increase their conception rate.


    We should start as early as possible during the breeding season. Even if we don't care about getting early foals for the competitive advantage this can have for young horses, the problem mare may take more time to conceive. By placing these mares under artificial lighting on December 1, (8 hours of darkness, 16 of light) most will have a fertile cycle about February 1. This gives us an average of two extra cycles per year--more than in natural lighting--and hopefully, we won't see October with an empty mare and a large vet bill.  


    Careful management includes knowing the time of ovulation. The use of hormonal therapies to stimulate ovulation allows us to breed only one time per cycle.  Fertility is a matter of timing rather than frequency-- sperm cells present in the uterus at the time of ovulation present our best chance for establishing a pregnancy. In problem mares, multiple covers increases the chance of infection which impairs fertility.


    Accurately assessing the time of ovulation allows us to implement several treatment options. There is a five or six day window between conception and the arrival of the fertilized ovum in the uterus. This gives us time to remove excessive fluid, institute treatment for infection and address luteal insufficiency with synthetic progestagins (i.e. Regumate) in mares that need it.  It is not a good idea to "shotgun" problem mares with synthetic progestagins.


    Our management plan for problem mares should include, but not be limited to:

    1).  Placing the mare under lights December 1 for a period of 16 hours of light and 8 hours of dark.

    2).  Vet exam with ultrasound to assess the lining of the uterus

    3).  Daily teasing with the stallion. Uterine culture and cytology during the first two days of standing heat.

    4).  Hormonal stimulation of ovulation, breed once, follow up exams daily to assess the time of ovulation.

    5).  Treatment plan dictated by ultrasound assessment and the results of the culture. (If timed right, this can happen during the same cycle).

    6).  Blood tested for progesterone level five days after ovulation to determine luteal function. Consider starting on supplemental progestagins on day five. This hormonal treatment can be stopped if the test comes back normal, but it is better to have this compound on board by day five.


    The average conception rate is about 60% per cycle.  So keep trying.  With careful management and a little luck, you'll have another mouth to feed next year. Madison Seamans, DVM, MS, Cornerstone Equine Medical Service, Wilder, Idaho

  2. I was told it is not wise to breed an Appaloosa to an Appaloosa. What issues would this present, and what are the chances of a normal Appaloosa coat? Please advise. (View Answer)

    The question of breeding horses opens the proverbial "can of worms" for a lot people.  One concern for breeding Appaloosa horses is due to a serious eye problem known as equine recurrent uveitis (ERU). Though the exact cause is not clear, there have been twelve genetic markers reported in horses with ERU. These are not limited to Appaloosas, and the test is not yet commercially available--and that 's the bad news. Thankfully, there are tests for other genetic flaws that can help us select our breeding stock, regardless of registration. (See the Appaloosa horse club website for a list of their favorites) 

    Without testing, it may be impossible to know if a given horse has genetic flaws, which may be passed on to future generations. To make things even more complicated, recent research demonstrates the passage of some orthopedic and metabolic diseases not related to genetics, but transmitted directly from the mare!  With this in mind, we should be very careful in our reproductive choices, regardless of breed. Do not breed horses carrying diseases that can be identified by genetic testing. Do not breed horses with metabolic or orthopedic diseases (Equine metabolic syndrome, insulin resistance,  OCD or any lameness NOT caused by traumatic injury). The only way to remove undesirable traits from any breed or line of horses is to stop reproducing affected individuals. Thankfully, the Appaloosa Horse Club  allows "outside" blood. The policy stated in their website: "Pedigreed Appaloosas must have at least one ApHC-registered parent (sire or dam) classified as Regular (#). The other parent may be registered with the ApHC, or an ApHC-Approved Breed Association: American Quarter Horse Association (AQHA), Jockey Club (Thoroughbred), or Arabian Horse Association (AHA or WAHO)".  This is a very wise policy, as it will allow the infusion of desirable traits and provides at least the potential to remove undesirable ones from the gene pool. Madison Seamans, DVM, MS, Cornerstone Equine Medical Service, Wilder, Idaho

  3. I have a 16-year-old maiden mare that has gas ulcers off and on. I have been treating her with omeprazole as she does very well with it and has been able to keep the episodes at bay for 3 ½ months. Unfortunately, it is now back and am looking to treat another round. I am considering breeding her in February. Should I be concerned? (View Answer)

    EGUS (gastric ulcers in horses) has been carefully studied over the recent decade, and  our understanding of this very common syndrome has changed.  Omeprazole, (prilosec, gastroguard, ulcergard) js one in a class of drugs called proton pump inhibitors (PPI).  Although it has long been considered safe, recent evidence has suggested this type of compound must be used with caution.  In mares, the recommendation is: "The safety of omeprazole in pregnant and lactating mares has not been determined. Do not use in pregnant or lactating horses unless benefits outweigh the risks. Avoid use in foals less than 4 weeks of age."  In addition, horses experiencing multiple bouts of EGUS--even those that have responded to PPI's in the past--may benefit from other management techniques with lower to no risk. Slow feeders and natural products that elevate gastric pH (Aloe Vera juice and some seaweed extracts) have been a quite effective part of EGUS management. 


    To make things just a bit more complicated, sixteen-year-old-maiden mares can be a challenge on several levels. Older mares, especially maidens over the age of thirteen or so, will commonly be difficult to impregnate, so you are going to need help. You should seriously consider starting artificial lighting now. Sixteen hours of darkness and eight hours of light (bright enough for her to read a newspaper in every corner of her stall) will stimulate most mares to produce a normal ovulation cycle by the first of February.  Your local AAEP veterinarian can guide you through this aspect of equine reproductive and nutritional management.  Good luck, we hope you have a new mouth to feed in 2020! Madison Seamans, DVM, MS, Cornerstone Equine Medical Service, Wilder, Idaho

  4. What causes an 18-year-old maiden mare (never bred) to have a full bag from which I can squeeze liquid? In about October or November, she had a full bag for about a week, first time in her life that it's ever been that full; then it went back to normal. I've had her since she was born, so I have the opportunity to observe her year around, every year. I also have an 11-year-old gelding in the herd. (View Answer)

    Mammary development, or what looks like it, can occur due to several reasons. First, the mare is pregnant. You should have a veterinarian perform a pregnancy exam to be absolutely sure.  There are many cases where "she can't be pregnant, there is no stallion around!", but the mare, indeed, was "expecting".  Hormonal influences are a powerful force which has insured the survival of the species:  boys and girls will get together.  There are many plants that contain phytoestrogens, a hormone that can mimic the  effects of naturally occurring substances that can cause mammary development in non-pregnant mares.  Soybean products are a good source of these compounds, so check any grain or "supplements" for the presence of soy-based material.  An infection in the mammary gland called mastitis can also cause a milky discharge, so a vet exam would also be helpful to diagnose and treat this problem. Finally, there are some mares that present with a "milk-like" secretion for absolutely no apparent reason. This will not likely be treatable, but also not a real problem, so therapy would not be warranted. Madison Seamans, DVM, MS, Cornerstone Equine Medical Service, Wilder, Idaho